PROJECT SUMMARY/ABSTRACT: PROJECT 2 Neuroinflammation is a major pathogenic factor in Parkinson Disease (PD). Both innate and adaptive immune cells, including microglia, macrophages and CD4+ T-cells, are involved in PD. The JAK/STAT pathway is the major signaling pathway used by cytokines, and is critical for regulation of immune responses. Our results demonstrate that hyperactivation of the JAK/STAT pathway causes dysregulation of innate and adaptive immune responses, leading to neuroinflammation and neurodegeneration in the AAV2-?-synuclein (syn) model. Importantly, therapeutic treatment with a JAK1/2 inhibitor (Jakinib), AZD1480, prevented neuroinflammatory and neurodegenerative responses. Furthermore, we have preliminary data demonstrating dysregulation of the JAK/STAT pathway in monocytes, CD4+ T-cells and CD8+ T-cells from patients with PD compared to controls, with observed sex differences. We hypothesize that in PD, abnormal forms of ?-syn cause altered activation of the JAK/STAT pathway, leading to pathogenic innate and adaptive immune responses. These events promote neuroinflammation and neurodegeneration, and suggest that therapeutic intervention in the JAK/STAT pathway will alter the progression of human PD. Project 2 of the Alabama Udall Center will examine how abnormalities in the JAK/STAT pathway in the context of a new pre-clinical PD model (Aim 1) and in patients with PD (Aim 2) promote dysregulation of both innate and adaptive immune cells, and how that impacts on the neuroinflammatory response and neurodegeneration. We have demonstrated that use of a Jakinib with specificity for JAK1/2 (AZD1480) is protective in the AAV2-?- syn PD model. Aim 1 will be the evaluation of targeting the JAK/STAT pathway in the new ?-syn preformed fibril (sPFF) model, that closely models human PD. We will test two novel Jakinibs which are both specific for JAK1, with one being brain penetrant and the other not. These novel reagents will allow us to determine the involvement of JAK1, JAK2 or both in PD pathogenesis, and test whether inhibiting signaling in the periphery is sufficient for protective effects. In Aim 2, we will directly test our hypothesis that there is dysregulation of the JAK/STAT pathway in human PD by examination of this pathway in myeloid cells, CD4+ T-cells and CD8+ T- cells from untreated, de novo PD patients. These studies will allow us to assess whether JAK/STAT pathway dysfunction occurs at the earliest stages of PD, and if this predicts more rapid progression of clinical symptoms, with a focus on cognitive symptoms. Collectively, the proposed studies will address an unanswered question in PD: is activation of the JAK/STAT pathway in the periphery and/or brain an important contributor to neuroinflammation and neurodegeneration?